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interception of convoys

...rescue ships, and voice radio communications permitted convoys to be more easily coordinated, and afforded greater protection against the new German tactics of marshalling U-boats into “
wolf packs” of 8 or even 20 submarines that would intercept convoys and attack them at night en masse. The effectiveness of the convoy system during World War II can be seen in the fact that of...

significance in naval tactics

Barring a brief period in 1942–43, when U-boats operated successfully in so-called
wolf packs, submarines have always been solo performers, relying for successful attack on concealment and surprise rather than concentration of force. These tactics, quite different from fleet actions, are akin to guerrilla war at sea. The submarine stalks its prey while the target—a warship, merchant...

use in World War II

...device to detect submerged U-boats. By the spring of 1941, under the guidance of Admiral Karl Dönitz, the U-boat commanders were changing their tactic of individual operation to one of wolf-pack attacks: groups of U-boats, disposed in long lines, would rally when one of them by radio signaled a sighting and overwhelm the convoy by weight of numbers. Between July and December 1941...